We don’t collect Bill address and ZIP at all, so you can just leave them blank.
Here is the detail:
1 After adding the product into the cart, go to the cart, then press the button [Processed to checkout]
2 On the billing details page, leave everything blank(They are all optional), except email address, we need this to send you the order notification.
Press Paypal, you will be redirected to Paypal to finish the payment.